Writing utensil



Aug. 5, 1969 F. MATSCHKAL WRITING UTENSIL Filed Aug.

LNVENT'DR v ruwz. MRTScaKAL BY Rom cw) B l rroausYs United States Patent 3,459,486 WRITING UTENSIL Franz Matschkal, Nuremberg, Germany, assignor to J. S.

Staedtler Kommanditgesellschaft, Nuremberg, Germany, a German company Filed Aug. 3, 1967, Ser. No. 658,113

Claims priority, application Germany, Aug. 5, 1966,

Int. Cl. B43k 5/00 US. Cl. 401-259 7 Claims ABSTRACT OF THE DISCLOSURE A writing utensil in which the writing fluid such as ink is supplied to the writing point from a storage chamber within the utensil and make-up air is admitted into the chamber through an air duct. Excessive outflow of ink near the writing point due to a pressure build-up in the storage chamber as caused, for instance, by a sharp temperature increase, is avoided by a pressure compensating chamber in which an excessive outflow of ink due to the pressure build-up is accumulated and from which it is gradually discharged when the pressure build-up subsides.

The invention relates to a writing utensil for use with a liquid writing fluid such as ink, India ink, tints, etc. and more particularly, to a fountain pen of the kind in which an air duct within the shell of the utensil connects the ink storage chamber of the utensil with the writing assembly thereof and in which the ink is supplied from the storage chamber to the writing assembly by a feed duct.

With writing utensils of the general kind above referred to, a uniform flow of the ink or other writing fluid from the storage chamber to the writing assembly is obviously necessary to permit smooth writing. Precautions must be taken that a temporary pressure build-up in the ink chamber does not cause an excessive outflow of ink. Such excessive outflow tends to result in the escape of drops of ink and smudges. It must also be avoided that crusts formed by dried ink prevent or at least impede the free flow of liquid ink to the writing assembly.

It has been found that with writing utensils of the general kind above referred to a pressure build-up occurs rather frequently in the ink storage chamber, for instance, when the writing utensil is exposed to higher than usual temperatures. Such pressure build-up forces the ink into the air duct generally formed between the shell of the utensil and the writing assembly, the latter being usually threaded into the shell. The excess ink tends to enter the air duct near the outer end of the air duct and hence, can no longer reach the writing point. It also results in smudging the closure cap of the utensil and the entire front end thereof.

Moreover, the ink in the air duct when dry, impedes or even blocks the flow of air into and out of the ink chamber thus preventing pressure compensation therein and as a result, the utensil is no longer in condition for immediate use.

It is a broad object of the invention to provide a novel and improved writing utensil of the general kind above referred to in which an excessive outflow of the Writing fluid due to a pressure build-up in the torage chamber is effectively avoided and a smooth communication of the chamber with the outside air is assured.

A more specific object of the invention is to provide a novel and improved writing utensil of the general kind above referred to in which a normal pressure is continuously maintained in the ink storage chamber by means of a pressure compensating chamber which communicates Patented Aug. 5, 1969 ice with the air duct and also with the feed duct of the utensil.

According to one exemplification of the invention the pressure compensating chamber is formed by a sleeve surrounding the feed duct spaced apart therefrom. The feed duct has in its wall an aperture leading into the compensating chamber and the sleeve has an aperture communicating with the air duct. The aperture between the feed duct and the pressure compensating chamber is preferably provided near the end of the feed duct adjacent to the writing assembly of the utensil and the aperture leadin g from the chamber into the air duct is preferably provided near the other end of the chamber.

The air duct may be formed, at least in part, by a lengthwise groove in the outer wall of the sleeve.

The invention further provides that the end walls of the sleeve are used as holders for the feed duct which is preferably in the form of a tube extending through said end walls. The sleeve itself is held in the shell by means of a partition wall thereof.

If India ink or tints are used as writing fluid, the aperture leading from the compensating chamber into the air duct is preferably fitted with a liquid impervious but air permeable plug, for instance, a porous plug made of metal or plastic and saturated with silicon oil.

As an alternative, the invention further contemplates to provide within the compensating chamber a spiral winding encompassing the feed duct extending through the chamber. Such spiral winding serves to assure a smooth air flow within the compensating chamber.

In the accompanying drawing several preferred embodiments of the invention are shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a lengthwise sectional view of the front portion of a Writing utensil according to the invention;

FIG. 2 is a section taken on line IIII of FIG. 1;

FIG. 3 is a section taken on line III-III of FIG. 1;

FIG. 4 is a section taken on line IV-IV of FIG. 1; and

FIG. 5 is a section taken on line VV of FIG. 1.

Referring now to the figures more in detail, the shell of the utensil is a two-part shell only the front portion 1 of which is shown. The front portion should be visualized as being screwable upon the rear portion by means of the indicated threads.

The shell portion 1 mounts in its front and the writing assembly proper which should be visualized as being generally conventional. It comprises a holder 2 in which is mounted a writing sleeve 3 which constitutes the writing point proper. A valve member or plunger 4 is slidable in holder 2 so as to close the holder at 5 by gravity when the utensil is held with the writing assembly facing downwardly. A pin 4a on plunger 4 extends through sleeve 3 protruding therefrom. As is evident, pressure exerted upon the pin when the utensil is held in writing position pushes the plunger backwardly thereby opening a gap at 5 through which ink can reach the writing point from an ink storage chamber 12 in the rear end of the shell as will be more fully described hereinafter.

An air channel between holder 2 and shell portion 1 is formed by lengthwise grooves 6 and ring grooves 7 formed in threads 8 by means of which the writing assembly and more specifically, the holder thereof is secured in shell portion 1. The air duct is continued by annular spaces 25 and 26 and a groove 18 formed in the outer wall of a sleeve 13 as will also be more fully described hereinafter. As is evident, a continuous air duct leading to the forward end of shell portion 1 is thus formed so that the chamber is in communication with the atmosphere.

Holder 2 mounts a bushing 9 through which is extended a guide pin 10 secured to valve member 4. Pin 10 serves guide the plunger when sliding in holder 2 and may be long enough to reach into ink chamber 12.

A tube 16 communicates on one end with chamber 12 and on the other end with the gap controlled at 5 by plunger 4. As can clearly be seen in FIG. 1, there is a continuing passage for the flow of ink from chamber 12 into sleeve 3 via feed tube 16 when plunger 4 is in the position opening the gap at 5.

The pressure compensating chamber according to the invention is formed by the annular chamber 14 defined by feed tube 16 and sleeve 13 encompassing the tube spaced apart therefrom. An apertured end wall of sleeve 13 is used to mount the forward end of tube 16. The other end of the tube is secured by a Wall member 17 which also consttutes the forward end Wall of chamber 12, the other end wall being formed by the base of the rear portion of the shell (not shown).

Chamber 14 is defined by tube 16 and sleeve 13 communicates with the aforementioned groove 18 in the outside wall of sleeve 13 through an aperture or port 19 thus connecting the compensating chamber with the atmosphere. A second port or aperture 20 connects the compensating chamber with feed tube 16. The aperture 19 is preferably provided at the rear end of sleeve 13 and the aperture 20 at the forward end of tube 16.

A liquid impervious but air permeable plug 21 is fitted in port 20. Such plug may be made of porous metal or plastic and is saturated with a suitable liquid such as silicon oil. The plug may be omitted with certain types of writing utensils even if India ink is to be used as writing medium.

In addition to a plug a spiral winding as is indicated at 22 may be used. This winding is fitted into compensating chamber 14 encompassing tube 16 therein. Tests have shown that such spiral winding assures a satisfactory air flow.

The writing utensil as hereinbefore described functions as follows:

Let it be assumed that the utensil is used for writing. To compensate for the then consumed ink, a corresponding quantity of ink will flow from chamber 12 into sleeve 3 as previously described, the gap at 5 being open when and while pin 4a is pushed back by applying writing pressure to sleeve 3. At the same time make-up air will flow through grooves 6, 7, spaces and 26, groove 18 and aperture 19 into compensating chamber 14 and from this chamber through aperture 20 and feed tube 16 into chamber 12 thereby maintaining normal pressure in the same.

When now the utensil is exposed for any reason to an unusually high temperature the pressure in ink chamber 12 will automatically rise and as a result, more ink will flow out of chamber 12 than can be consumed. Such excess ink will flow through aperture 20 into compensating chamber 14 in which it accumulates. If now the excess pressure in chamber 2 subsides the air flowing into the compensating chamber through aperture 19 will press the ink accumulation in this chamber back into the feed tube 16 through aperture 20. Such pressed back ink will now be consumed in normal fashion and further ink will be supplied from chamber 12 as needed.

As is now apparent, the arrangement of the invention effectively prevents the ingress of ink into the forward grooves 6 and 7 of the air duct. In this connection, it should be pointed out that it is of particular importance that the air contained in compensating chamber 14 can escape through aperture 19 when ink flows into chamber 14 through aperture 20 in response to an elevated pressure in ink chamber 12, aperture 19 being always in direct communication with the atmosphere but blocked by plug 21 for the outflow of ink.

As it is shown in FIGS. 3, 4 and 5, feed tube 16 can be used to form an air channel 23 and a feed channel 24. There are shown in the figures two contiguous channels of which air channel 23 has the smaller cross-sectional area.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. A fountain pen comprising in combination:

a shell including in its rear end a storage chamber for writing liquid;

a writing assembly fitted in the front end of the shell;

a feed duct of non-capillary dimensions within the shell leading from said storage chamber to said writing assembly for feeding writing liquid thereto;

an air duct of non-capillary dimension extending within the shell and connected at one end to the atmosphere at a point near said upper end of the shell;

a pressure compensating means within said shell, said compensating means including a tubular member closed at both ends by end walls and encompassing said feed duct radially spaced therefrom to define an annular elongate compensating chamber between the tubular member and the feed duct, said feed duct having at its end adjacent to the writing assembly a first port communicating with the compensating chamber and said tubular member having at its end adjacent to said storage chamber a second port communicating with the other end of said air duct; and

a liquid impervious but air permeable plug closing said second port, said plug permitting passage of air into and out of said compensating chamber but blocking egress of writing liquid from said chamber.

2. A fountain pen according to claim 1 wherein said tubular member has in the outside of its wall a lengthwise groove, said groove constituting a part of said air duct.

3. A fountain pen according ot claim 1 wherein said plug is a rigid porous plug saturated with silicon oil.

4. A fountain pen according to claim 1 wherein said feed duct comprises a tube leading from the storage chamber to the writing assembly, and wherein a spiral winding within said compensating chamber encompasses the feed tube.

5. A fountain pen according to claim 1 wherein said feed duct comprises a tube leading from the storage chamber to the writing assembly, said feed tube extending through the end walls of the tubular member with a tight seal.

6. A fountain pen according to claim 5 wherein a partition divides said shell into two compartments, one including said writing assembly and the other said storage chamber, said feed tube extending through said partition wall and said tubular member abutting on one end against said partition wall.

7. A fountin pen according to claim 1 wherein said air duct and said feed duct are formed by a tube including two contiguous channels of differently dimensioned crosssectional areas, the channel having the larger cross-sectional area constituting the feed duct and the other channel the air duct.

References Cited UNITED STATES PATENTS 2,401,167 5/1946 Kovacs 401-259 2,766,728 10/1956 Kovacs 401-227 2,766,729 10/1956 Kovacs 401-225 2,891,512 6/1959 Kovacs 401-258 X FOREIGN PATENTS 950,633 3/ 1949 France. 1,244,806 9/ 1960 France.

LAWRENCE CHARLES, Primary Examiner US. Cl. X.R. 40l--217, 242 

